In order to provide television service to certain geographical areas that are not directly covered by transmitters associated with networks or other broadcasters, it is customary to provide one or more translators between such transmitters and the receivers located in these geographical areas. Each translator demodulates the signal from the transmitter or from another translator, re-modulates the demodulated signal, and transmits the re-modulated signal for reception by receivers in the affected geographical areas or by other translators.
Accordingly, in the process of supplying a broadcast signal from a transmitter to a receiver, it is possible for the signal to undergo multiple sequences of demodulation, re-modulation, and re-transmission. Because each of these sequences deteriorates the base signal, there is a practical limit on the number of the sequences that can be performed before the signal becomes unusable.
One of the main sources of this deterioration is phase noise (jitter) which is introduced into the signal through the mixing operation during each sequence of demodulation, re-modulation, and re-transmission. As the broadcast signal passes through each translator, phase noise increasingly corrupts the symbol clock as well as the byte clock that is typically derived from the symbol clock. Receivers using corrupted symbol and byte clocks have difficulty in properly decoding the received broadcast signals.
Moreover, new integrated circuits that are being used for demodulation of these broadcast signals often use sampled symbol clocks that contain artifacts that contribute to the deterioration of the signal.
The present invention is directed to the translation of signals in a way that reduces phase noise and/or artifacts in the symbol clock that is used during the demodulation, re-modulation, and re-transmission process.